[75.07] Using Time Variable Faraday Rotation Measures to Probe the Narrow Line Region in Quasars

Using the VLBA we have obtained high resolution
(submilliarcsecond) Faraday Rotation Measure (RM) images of
the quasars 3C273 and 3C279. Our 2000 January 27 observation
was made by combining observations at 8, 12, 15, 22, and 43
GHz. We see variations in the RM of these quasars on short
spatial (<10 pc) and temporal (3 year) scales. The most
striking variation on temporal and spatial scales occurs in
3C273. In our low resolution 8-15 GHz RM maps we see that
this quasar's central region has changed from a uniform
~ -2000 rad/{\rm m2} 3 years ago to a more complex
structure which ranges in {\mid{\rm RM}\mid} by ~
2500 rad/{\rm m2} over little more than 10 pc. Our high
resolution RM map resolves this structure into individual
components which change by 103 rad/{\rm m2} on the
scale of a few parsecs. The quasar 3C279 displays lower RM
values, but also exhibits a temporal variability over a
three year time span. We suggest that the variations in RM
in both quasars are due to the narrow-line region, which
acts as an irregular Faraday screen, sampled at various
lines-of-sight by the moving jet components.

The author(s) of this abstract have provided an email address
for comments about the abstract:
rzavala@nmsu.edu